Figure 3
The x-axis represents time from tunnel entry in seconds, and the y-axis represents the normalized velocity u/V. The red line shows the full-scale test data, and the blue line shows the present 1D solver data. Region A shows the piston wind ahead of the train, with measured and computed values close, differing by about 11 percent. Region B shows the nose passage transient, with a minimum value of about minus 0.099 versus minus 0.100, with timing within 0.06 seconds. Region C shows the annular gap and wake, where the probe records a near-body boundary-layer velocity not represented by an area-averaged model. The shaded band indicates the vertical extent of the plotted line. All values are approximated.Validation of the piston-wind field against the full-scale measurement of Fu et al. (2017) (1,005 m tunnel, A0 = 100 m2 double track, eight-coach trainset, 250 km/h, probe 500 m from the entrance). Region A, ahead of the train nose, compares like with like; Region B is the nose-passage transient; in Region C, the probe records a near-body boundary-layer velocity that an area-averaged formulation does not represent. The measured trace is digitised from the published figure, the shaded band being the vertical extent of the plotted line. Source: Author's own work